The site carries the name Cill Éinne, or the church of Aighne, and what makes it quietly odd is the density of reuse accumulated here over many centuries. A fragment of carved stone from the medieval building has been pressed into service as a gravemarker near the south-east corner. Part of a font basin turned up built into an overground tomb. A bullaun stone, a rounded boulder with a cup-shaped hollow that is typically associated with Early Christian sites, was once set into the graveyard wall; it now sits in the yard of the Roman Catholic chapel in Castlegregory. Stone foundations outside the south wall were, until recently, remembered locally as the remains of an ancient monastery, but they were destroyed when the graveyard was extended.

The church itself shows at least two distinct phases of construction. The rectangular structure, measuring roughly 15.7 metres by 5.67 metres internally, probably dates in part from the 13th century, though it was substantially rebuilt in the 15th or early 16th century. That later campaign added a residential tower to the south-east corner and a garderobe tower, essentially a latrine turret, to the south wall, suggesting the building had taken on a residential or semi-defensive function alongside its ecclesiastical one. The east gable and much of the north and south walls still stand close to their original height, and the remains of an elaborate roof drainage system survive, with transverse water channels feeding stone spouts below eaves level. The east window retains a trefoil-headed light within a double roll-moulded frame, and traces of a pink-coloured plaster wash can still be seen on the semi-circular rear arch of the south window. The parish church was first recorded in the Papal Taxation List of 1302 to 1307, noted as void by 1473, listed again among parochial churches in 1622, and recorded as ruinous by 1756. A Church of Ireland church was erected directly to the south in the early 19th century, and a large stone cross stands beside its south wall. About 500 metres to the north lies Tobar Éinne, a holy well associated with the same saint.